By the way, I don´t find these Sigma lenses great when shooting in the streets. Most due to the fact that the 7 has a very long startup time when using these lenses. (...) If suddenly you want to take a snap, you have to wait several seconds for the camera to get ready, and the situation you saw is gone. Very annoying....

I do not notice a longer startup time with the Sigma lenses compared to the Sony lenses (kit zoom and 16mm). What I notice is a longer startup time,
after having exchanged the lens
. For example, if I have the Sigma on, start/stop is instantaneous. I switch the camera off, put a Sony lens on, start will take much longer. Switch off, leave lens on, re-start: instantaneous. Change the lens back to Sigma or another Sony: have to wait when restart, etc...